The following application proposes to study the development of the nervous system in Drosophila melanogaster. The objectives are to generate a detailed fate map of adult and larval nervous system, to determine which tissue elements participating in the formation of a synapse are responsible for its normal development, and when in the developmental process events critical to normal synapse development are occurring. The study will make use of several mutants in Drosophila which seem to perturb synapse formation. These will be studied using light and electron microscopy to determine the precise nature of the perturbation. Genetic mosaics created both by somatic recombination and by gynandromorph formation will be used to study the interaction of mutant and normal tissue and also to elucidate the normal embryogenesis of the nervous system.